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I had a 4 ton Carrier Infinity heat pump (2 speed with VS fan coil) installed (attic) two months ago. Just turned on the AC two weeks ago. The system is qreat - cools well, even temperature throughout house, and is quiet (except on high). Checking the system through the stat, I noticed that static pressures were higher than I expected based on general information I have picked up on this site.
882 CFM -- 0.35
1400 CFM --0.97
1600 CFM --1.19
The system typically operates in the 800 to 1400 CFM range and only goes to the highest speed when there is a >2°F difference in actual and demand temperatures. The installer says these readings are normal. Also, the stat called for filter cleaning after only 1 week of operation. I cleaned it even though it looks brand new. After 1 more week it is calling for cleaning again. No faults are reported. Any thoughts?

1400 at .97,is too high,little room left as the filter gets dirty to stay below the limits..70 is the max we leave them at ,with a clean filter.1600,will likely be so few times,if set for 350 cfms,that it can be over the limit.

It's likely a simple duct modification to get it down,can you post pictures of the ducts?

Location: Sacramento CA (currently 107°F)
Ducts are all flex with a centrally located 20 x 30 return grill (alergy gold electrostatic filter) and a 16"dia duct. There are 6 supply ducts off the plennum: 1-5", 2-6", 1-8", 1-10", and 1-14". The 6" and 8" ducts have dampers. Looks like the size on the return duct is limited by the roof line in the attic.

Originally posted by rkmx5 The merv 8 filter is a naturalaire 1" thick. I put a cheap fiberglass filter in and the SP dropped to 0.82. Without any filter the reading was 0.71. I guess filters do make a big difference